1. Field of the Invention
The present invention relates to a circuit board device with a multilayer chip capacitor mounted thereon and an integrated circuit device, and more particularly, to a circuit board device and an integrated circuit device capable of effectively removing high frequency noise while retaining high rated-current characteristics and simplifying a power circuit configuration.
2. Description of the Related Art
A multilayer chip capacitor (MLCC) is favorably used as a bypass capacitor disposed within a power circuit of LSI (Large Scale Integration). To serve as the bypass capacitor, the MLCC needs to effectively remove high frequency noise. Such a need is increasing in line with the trend toward high frequencies in electronic devices.
A general MLCC used as the bypass capacitor has a two-terminal structure as shown in FIGS. 1A and 1B. The two-terminal structure refers to a structure in which an MLCC 10 is mounted in a configuration in which two outer electrodes are connected to a circuit board. The related art two-terminal MLCC 10 includes a capacitor body 11 having a laminated structure of dielectric layers 14, and first and second outer electrodes 12a and 12b each formed with a different polarity on an external surface of the capacitor body 11. First and second inner electrodes 13a and 13b are laminated within the capacitor body 11, alternated with the dielectric layers 14, and are connected with the first and second outer electrodes 12a and 12b, respectively.
FIG. 2 is an equivalent circuit diagram schematically showing noise bypassed via the MLCC. The MLCC used as a bypass capacitor may be electrically connected to a pad mounted on the circuit board through soldering, and the mounted pad may be connected to an external circuit via a wiring pattern or a conductive via of the substrate. In detail, as shown in FIG. 2, the MLCC is connected to a power line and a ground line. In particular, the MLCC is vertically connected to the power line.
In this case, however, the MLCC has both equivalent series resistance (ESR) and equivalent series inductance (ESL) components in addition to a capacitance component, and such ESR and ESL components degrade the function of the bypass capacitor. In particular, the ESL components increase the impedance of the capacitor at high frequencies to degrade high frequency noise removing characteristics. The inductance (L) of the bypass capacitor may differ depending on how the MLCC is mounted and structured, and these differences in the inductance of the bypass capacitor significantly affect noise removing characteristics.
In order to effectively remove high frequency noise, a method for using a plurality of MLCCs as shown in FIG. 3 may be taken into consideration. However in this method, the increase in the number of capacitors makes the power circuit configuration complicated.
Thus, a power circuit is required, which employs a smaller number of bypass capacitors to realize a simplified circuit configuration and effectively remove noise.